An automobile is provided with a battery as a power source, and the battery can be recharged by means of a generator in the automobile. Referring to FIG. 6, there is shown a basic electrical connection diagram, according to which, a positive side of a battery 900 is electrically connected with an electrical equipment 910 which includes air-conditioner, headlights, and audio, for example, whereas a negative side of the battery 900 is electrically connected with an engine 920. Further, the electrical equipment 910 is shown to be at the negative side thereof electrically connected with a vehicle body 930 (body of automobile), while the afore-said engine 920 and vehicle body 930 are shown to be grounded. It is seen from the diagram that a direct current is supplied from the positive side of the battery 900 to the electrical equipment 910 and then passes through the vehicle body 930 and engine 920 to reach the negative side of the battery 900.
The foregoing arrangement certainly establishes a ground for the automobile or vehicle, though either the engine 920 or the vehicle body 930. But, such grounding may not completely allow sufficient flow of electric current to a ground, which will result in a whole of the vehicle body being still electrically charged, thus raising the problem that a noise may be generated in audio device, or firing of engine may not be done satisfactorily, for instance.
Solution to the problem stated above can be found from the under-mentioned patent-related document 1 titled “Earthing System and Earthing Method”. According to that literature, a negative terminal of battery and an engine ignition system are electrically connected together by use of an earth cable which is composed of complex line formed by a plurality of thin wires.